Art of processing citrus fruits



Patented June 15, 4937 ART OF PROCESSING CITRUS FRUITS Robert D. Nedvidek, Pomona,

and John B.

MacRill, Norwalk, Calif., assignors to California Fruit Growers Exchange, Los Angeles, Calif., a corporation of California No Drawing. Application March 29, 193d, Serial No. 440,156

12 Claims.

Those conversant with the art of processing citrus fruit are well aware of the number of difficult problems which must be met and disposed of before oranges and other citrus fruit are successfully and economically brought from the groves and placed in the hands of the ultimate consumer. The major problem in this art is that of cleaning and conditioning thefruit in such a. way that it may reach the market inthe most satisfactory and successful condition. This problem includes the treatment of the fruit so as to prevent the development of molds thereon and the elimination of insect life on the fruit.

Fruit fresh from the grove is never clean. Citrus groves are always carefully cultivated, which gives rise to quantities of dust and dirt, which in turn collect on the fruit. Furthermore, citrus groves are generally sprayed for the control of various insects,'fungi and the like, and the sprays 2O always leave residues on the fruit.

Furthermore, mealy bug deposits, black scale deposits, otherinsect deposits of various kinds and black smut are all found in varying amounts on the fruit. From time to time, whenever it is necessary to warm the groves by the procedure known as smudging, a considerable deposit of soot or smudge necessarily occurs on the surface of the fruit. Obviously, any and all of the foregoing materials, as well as any other similar foreign matter must be completely removed from the fruit and the surface given a rather glossy polish, before it is ready for marketing. Polishing the fruit enhances its appearance and, therefore, its sales value.

In addition to the above, fruit coming from the groves to the packing houses is frequently found to be infested with the bean thrips or Heliothn'ps jascz'atus as well as other forms of insect life. The fruit may, moreover, be infected 40 with the well known blue mold or other molds,

and in its natural state the fruit is highly susceptible to mold infection, which may occur during and by the packing house handling alone.

It is apparent that before fruit may be placed on the market it must likewise be free from any insect infestation and should preferably be rendered immune to the attack of the blue mold and/ or other molds as well.

Our invention relates to new and useful improvements in the art of cleaning and conditioning fruits, by means of which the processing of the fruit is greatly simplified and rendered more effective.- I

Another object of this invention is to disclose and provide a new and useful process of simultaneously cleaning and conditioning fruit, and particularly citrus fruit.

A still further object of our invention is to disclose and provide a process by which citrus fruits are quickly and easily freed from dirt, insect deposits, residues and other foreign matter.

Another object is to disclose and provide a new and useful method by means of which the bean thrips and other insect pests are effectively eradicated from citrus fruits.

A still further object is todisclose and provide a method of treating citrus fruits fresh from the grove, by means of which insect deposits, residues, and other foreign matter are removed from the fruit, and simultaneously the fruits are rendered highly resistant to the attack of molds.

Another object is to disclose and provide a process by means of which insects, insect deposits and foreign matter are removed from citrus fruit and simultaneously a waxy material is applied thereto, by means of which the appearance of the fruit is greatly enhanced.

Another object is to disclose and provide a method by means of which citrus fruit fresh from the groves may be treated for the removal of in-. sects, insect deposits and other foreign matter, and simultaneously covered with asubstantially intangible film of waxy material containing a mold inhibiting agent.

A still further object is to provide a method by means of which citrus fruits are freed from dirt, deposits, residues and other foreign matter, the bean thrips and other insect pests are effectively eradicated from the fruit, the fruit is rendered highly mold-resistant and is given a bright, polished appearance, all of which is accomplished quickly and easily in a single operation.

An object of this invention is to disclose and provide a. combined washing and conditioning solution for use in the treatment of citrus fruit.

Another object is to disclose and provide a solution containing a hydrocarbon dispersed therein, such solution being particularly adapted for the simultaneous cleaning and mold inhibiting treatment of citrus fruit.

Still other objects and advantages of our invention will become apparent to those skilled in the art from a contemplation oi the invention as set forth hereinafter.

Although the prior art has disclosed methods by means of which citrus fruits could be treated so as to inhibit the development of molds, the prior art has not disclosed a method by means of which the fruit could be freed from insect pests, such as the bean thrips. The bean thrlps,

Heliothrips jasciatus, referred to above is most particularly difllcult to eradicate, due to its habit of secreting itself under the button of the fruit and in the navel of the navel orange. There, minute air pockets are formed which enable the insect to be protected from the influence of any liquid with which the fruit as a whole may be placed in contact. These minute air pockets are not ordinarily penetrated by washing or treating fluids, and even when penetrated to some extent by those fluids in use heretofore, suflicient amounts of the material did not reach the insect to completely destroy it.

In the use of our invention, and particularly by the use of the particular treating agents defined hereinafter, all parts of the most minute crevices of the fruit are effectively reached and completely cleansed, and thus any insect infestation is completely eradicated.

Furthermore, although ordinary soap solutions have been employed in the cleansing of citrus fruits for a great many years, such prior cleansing solutions have not been capable of effectively removing all of the various forms of foreign matter with which the fruit is commonly covered. In other words, although ordinary dust and dirt could be removed by such prior cleansing solutions, the oily smudge or smut and insect deposits could not be completely removed without the use of other specially prepared solvents, which in turn did not successfully remove dirt or smudge. Furthermore, strong cleansing solutions and solvents tend to remove the naturally occurring waxes present in the skins of the fruit, such wax removal accelerating ,the wrinkling and shrinkage of the fruit.

Briefly, our invention comprises soaking and/or washing and/or treating the fruit in a speoiflc and predetermined manner with certain materials or combinations of materials, all as set forth hereinafter, so as to simultaneously cleanse the fruit and condition the fruit, whereby the fruit is rendered highly resistant to attacks by molds and so treated as to present a polished and glossy surface. The wax content of the fruit, by this method, is maintained at or above the content of natural waxes present in the skins of the fruit, thus preventing wrinkling or shrinkage. In order for those skilled in the art to practice the invention, more specific forms of the various materials and modes of operation will be set forth below.

In practicing the invention we may employ as a base a soap solution. Such soap solution preferably contains an emulsion. The emulsion may be either a kerosene emulsion, or an emulsion containing a mold inhibiting agent, such as pine oil; or both may be employed together.

. Pine oil is a light colored liquid of lighter speciilc gravity than water, obtained by extraction with a petrol solvent from pine chips. Pine oil normally contains borneol, alpha terpinol and dipentene. It has been found that in the preparation of these emulsions it is highly desirable to employ a water soluble soap, and preferably an oleic acid soap of high purity. It has been found that an ethanolamine soap, such as tri ethanolamine oleate, produces emulsions which disperse readily when added to the basic soap solution, and which are thoroughly dispersed in the soap solution, thus assuring the penetration of all crevices and apertures in the fruit with the treating solution. Such penetration is, as stated hereinabove, essential in order to eradicate insect pests such as the bean thrips, inasmuch as such thereto about 1%, and preferably less than 2%,

of an oleate soap of the character described hereinabove, on the total weight of kerosene and water.

When an oleic acid soap is used, quantities as small as 1 quarter of an ounce of soap per gallon.

of kerosene may be successfully employed. Preferably, the soap is dissolved in the water and the kerosene then added with agitation, so as to get a good emulsion. More thorough agitation is needed when small quantities of soap are'used.

The kerosene may contain paraflin wax, vegetable oil, mineral oil or liquid petrolatum, or mixtures of these ingredients. The paraflin and/or wax may be used in varying amounts,.such as from 0.05 to 1 pound per gallon of kerosene or other hydrocarbon solvent of this type. When wax is used, it may be melted and poured into the kerosene or shaved or disintegrated and allowed to dissolve therein. When vegetable oil is employed, from about 0.1 to 1 quart of oil may be added per gallon of kerosene; when mineral oil is used it may be added in the proportion of about 0.05 to 0.4 quart per gallon of kerosene.

It is to be understood that when two or more of the above substances are combined in the kerosene, the maximum proportions given above should not all be used together, although greater than the minimum proportions given may be used in combination. The exact proportions can be readily adjusted accordingto the result desired, and when one of these ingredients is increased the others may ordinarily be reduced correspondingly.

As an example of the type of emulsion deflned hereinabove, we may take pounds of kerosene containing 1 to 10% of a vegetable oil such as linseed oil or cotton seed oil; 6 pounds of triethanolamineoleate are thoroughly dissolved in the kerosene, and such kerosene then thoroughly mixed with water in the proportion of from 2 to about 3 partsof kerosene to 1 part of water. An

emulsion made as above described, using 1% of vegetable oil and 2 parts of the kerosene to 1 of water will give a reading on the Du Nouy tensiometer of about 48 dynes per centimeter. When this emulsion was diluted with 4 parts of waterto give a 20% bath, the reading was 43.1 dynes; dilution to a 1% bath gave a reading of 55.3 dynes.

As another speciflc example of an emulsion coming within the general class described hereinabove, we may take 4-parts of kerosene containing from 2 to 20 quarts of vegetable oil per 20 gallons of kerosene, and add to it about 6% by weight of oleic acid. Such kerosene may then be intimately mixed to 1 part of water to which has been added triethanolamine in the amount of about 2% by weight on the basis of the weight of the kerosene. This emulsion, prepared by using 2 quarts of vegetable oil and diluting with 4 parts ofwater (to give a 20% concentration) gave a reading with a Du Nouy tensiometer of 34.4 dynes per centimeter. When it was prepared by using 7 2,084,062 20 quarts of vegetable oil and was similarly diluted, the reading was 38.8 dynes. Whenever greater dilutions are employed, the surface tensions are higher (up to 50-53 dynes). when the diluent is a soap solution, the soap assists in reducing the surface tension.

It is to be understood that pine oil emulsions may be used in conjunction with the kerosene emulsion in the bath. For example, the emulsion may be produced by employing 1 part of kerosene, 1 part of pine oil and 1 part of water, the emulsifying agent in this case being about 1% of the total weight of a suitable soap, gelatin, or other emulsifying agent stable in alkaline solutions.

A pine oil emulsion may be prepared, for example, by intimately mixing 6 parts of pine oil with about 5% by weight of oleic acid and 2% by weight of triethanolamine, said triethanolamine being dissolved first in 4 parts of water.

A pine oil emulsion may be added to a soap solution in sufficient quantities so as to produce a final concentration of pine oil in the bath of. from about 0.02% to 0.25%. Preferably, the final concentration of pine oil should be kept within the limits of about 0.06% to 0.15%. Sufficient soap should be used to form a good suds. More may be added as and if needed. The temperature of the bath is preferably about to 120 F. and the time of contact with the fruit is preferably about 2- to 6 minutes. A kerosene emulsion of the type described above may be added to the soap solution. This may vary over the range & to 20%, on the basis of the water of the soap solution, and will be regulated in accordance with the character of the fruit to be cleaned and conditioned; it being obvious that very dirty fruit requires more cleansing agent, and vice versa. Thus when comparatively clean fruit is being handled, comparatively small amounts of a kerosene emulsion comparatively rich in oily and/or waxy ingredients may be used.

It is to be understood that in each of the emulsions mentioned hereinabove, whether kerosene or pine oil emulsions, the ingredients such as parafiin and/or wax and/or vegetable oil and/or mineral oil or liquid petrolatum may be used. It is particularly desirable to employ a waxy material such as paraffin when pine oil is used inasmuch as the pine oil is dissolved in the wax or liquid petrolatum and forms an unsubstantial film on the treated fruit, such film imparting a. glossy appearance to the fruit and containing the pine oil in insignificant quantities, but quantities sufficient to retard the development of molds on the fruit. When other waxes are used, a wax such as beeswax or carnauba wax is preferred.

The emulsions of the character described hereinabove may be prepared and then added to a suitable soap solution in the washing tank.

In addition to or instead of treating the fruit with an emulsion or combination of emulsions as set forth above we may treat the fruit with a slightly different type of kerosene emulsion. For example, we take about 95 gallons of water and dissolve in it about 7 pounds of a good commercial soap powder. We find that a soap powder made from cotton seed foots and cocoanut oil, and-which contains about 35% of soda ash is very satisfactory for the purpose of this invention. In fact, we have found that the use of soda ash in conjunction with emulsions of the type here disclosed is desirable as, for example, in that soda ash increases the stability of the resulting solution or emulsion. To this soap powderwater mixture we add a kerosene emulsion consisting of about 5 gallons of kerosene and 2 gallons of water in which 10 ounces of an oleic acid soap of high purity have been dissolved.

The final concentration of kerosene in the final emulsion consisting of the soap solution and the more concentrated kerosene emulsion, should preferably be maintained at about 5%, for the sake of economy, although the kerosene emulsion may be added to the soap solution in quantities sumcient to increase the content of kerosene in the final treating solution or emulsion. The bath prepared in this manner is kept at a temperature of from about to F., and the citrus fruit submerged in it for a period of time of from about 4 to 10 minutes, and preferably about 5 minutes. Such treatment is especially efficacious in eradicating the Heliothrips fasciatus and simultaneously removing any and all dirt, deposits or other foreign matter from the fruit.

Although it was stated hereinabove that the fruit is to be submerged in the treating bath, it is to be understood that complete immersion may not be entirely necessary, it only being desirable that all portions of the fruit be thoroughly .contacted with the treating solution.

After the fruit have been immersed in the treating bath, they may pass to brushing rolls where the fruit is sprayed, preferably with the same solution as that existing in the bath. When fresh water is employed for spraying purposes, it should ordinarily be confined to the latter half of the brushing rolls.

After leaving the brushing rolls, the fruit may or may'not go into additional tanks for further treatment. Such additional tank or tanks may contain a solution similar to that in the first tank, and/or other agents such as mold retarding agents which it is desired to have come in contact with the fruit. Inasmuch as the fruits are now in a thoroughly cleansed condition, the effect of the mold inhibiting or retarding agents on the fruit is enhanced when such agents are used in subsequent tanks. After such complete treatment the fruit is then disposed of in known ways, according to packing house methods. In case of lemons going to storage, for example, the fruit need not be dried or brushed, whereas fruit being sent to packing and shipping operations is preferably dried and brushed. Dry lemons, that is, lemons coming out of storage, particularly when not originally treated in accordance with the method of this invention, may be advantageously subjected to the action of the cleansing and conditioning solution of this invention upon being removed from storage.

In general, therefore, this invention relates to a simultaneous cleaning and treatment of citrus fruits by means of an aqueous soap solution containing a kerosene emulsion and/or a pine oil emulsion, or a mixture of pine oil and kerosene in emulsified condition, the oily ingredients such as pine oil or kerosene being in the internal or dispersed phase.

In this manner the fruit is completely cleansed and at the same time thoroughly freed from infection and insect infestation. Moreover, treatment of the fruit in accordance with this invention retards decay from green or blue mold as well as other forms of diseases, such as Alternari. If a pine oil emulsion is used, the pine oil apparently is absorbed in the waxy outer coatings ordinarily found on the fruit and thus retained on the fruit in the form of an inhibiting agent. The emulsions of kerosene, etc., described herein, may be contacted with fruit after the fruit have been cleansed by some other method;

Fruit treated with this invention are substantially tree from tangible evidence of the presence of ioreign matter. In other words. the pine oil concentrations are of such order that their odor is not perceptible. When waxes or heavy oils, such as vegetable oils or mineral oil are emplayed in the emulsions. the quantities employed are not suflicient to form a film on the outer surfaces oi the fruit which is perceptible to the touch, and the only indication of their presence is the glossy, polished appearance or the fruit. Furthermore. the use oi. kerosene emulsions of this type does not result in fruit which bear the odor of kerosene.

In addition, the invention contemplates the use 01' a soap such as triethanolamineoleate. It should be understood that wherever we have spoken oi triethanolami-ne we have had reference to the commercial product which apparently contains about to triethanolamine, 20 to 25% diethanolamine and 0.02 to 5% of monoethanolamine. Any one oi the pure substances would, of course, give equally satisfactory results, the proportions being varied correspondingly.

Having thus completely disclosed our invention in the manner in which the same is to be used, we claim as our invention the following:

1. Ina method 01' conditioning fruit, the step oi. cleansing the fruit, and dissolving pine oil in the natural waxy coating of the fruit during such cleansing operation.

2. In a process of conditioning fruit, the steps of maintaining fruit fresh irom the grove for a period 0! from 2 to 6 minutes in an aqueous soap solution containing not more than 15% or an emulsion of kerosene, paraflln, pine oil and triethanolamineoleate, the pine oil being present in concentrations between 0.06% and 0.15%, the bath being maintained at a temperature 01' between and 120' I".

3. The process oi conditioning citrus fruit which comprises contacting the fruit 'with a warm, aqueous soap solution containing ethanolamine soap and kerosene, pine oil and a wax dispersed therein, the pine all being present in concentrations between 0.02 and 025%, said soap solution containing not more than about 10% of kerosene.

4. The process of conditioning citrus fruit which comprises contacting the fruit with a warm, aqueous solution containing kerosene and pine oil dispersed therein, the pine oil being present in concentrations between 0.02 and 0.25 per cent, and the solution containing about 5 per cent of kerosene.

5. The process of simultaneously cleansing and conditioning citrus fruits, which comprises submerging citrus fruit from the groves in an aqueous soap solution, to which has been added emulsions of kerosene and pine oil in water in quantity suflicient to produce a concentration 0! about 5% kerosene and between 0.06 and 0.15% pine oil in such aqueous soap solution, and maintaining the citrus fruit in such solution for a period oi from 2 to 10 minutes at a temperature at about to F.

6. The process 0! simultaneously cleansing and conditioning citrus fruits, which comprises sub merging citrus fruit from the groves in an aqueous soap solution, to which has been added from to 20% of a kerosene emulsion and an emulsion of pine oil in water in amounts suiilcient to produce a concentration of between 0.06 and 0.15% pine oil in such aqueous soap solution, and maintaining the citrus fruit in such solution for a period of iron 2 to 6 minutes at temperature of about 110 to 120 1''. q

7. The process of conditioning fruit which comprises contacting the fruit with an aqueous soap solution to which has been added an emulsion oi pine oil, a waxy material and water, said emulsion containing an ethanolamine soap, said emulsion being added in such quantity as to produce a concentration of between 0.06 and 0.15% pine oil in said aqueous soap solution. and maintaining the citrus fruit in such aqueous soap solution containing pine oil and waxy material for a period of from 2 to 10 minutes at a temperature of about 100 to 120 1"., whereby the fruit is cleansed, Heliothrips lasciatus is eflectively eradicated, and an insubstantial waxy coating is applied to the fruit, said waxy coating containing pine oil dissolved therein.

8. In a process 01' conditioning fruit, the steps I, of maintaining fruit fresh from the grove for a period of from 2 to 6 minutes in an aqueous soap solution containing not more than 15% of an emulsion of kerosene, parailin and triethanolamine oleate, the bath being maintained at a temperature of between 100 F. and 120 F.

9. Theprocess oi simultaneously cleansing and conditioning citrus fruit which comprises submerging citrus iruit irom the grove in an aqueous soap solutionto which has been added a kerosene emulsion containing a vegetable oil, paraflln and an ethanolamine soap, the fruit being maintained in such solution for a period of time of from 2 to 10 minutes at a temperatureoi from 100 F. to 120 1"., the solution containng not more than about 10% of kerosene.

10. In a process of conditioning fruit, the steps oi maintaining fruit fresh from the grove for a period of from 2 to 6 minutes in an aqueous soap solution containing not more than 15% of an emulsion of kerosene, paraflln, triethanolamine oleate, and a terpene-containing mold-inhibiting agent in solution in the kerosene, the bath being maintained at a temperature of between 100 1". and 120 1''.

11. In a process of conditioning fruit, the steps of maintaining fruit fresh from the grove for a period of from 2 to 6 minutes in an aqueous'soap solution containing not more than 15% of an emulsion of kerosene and wax. and an emulsifying agent, the bath being maintainedat a temperature of between 100 F. and 120 1".

12. In a process of conditioning fruit, the steps of maintaining fruit fresh from the grove tor a period or from 2 to 6 minutes in an aqueous solution containing not more than 15% of an emulsion of kerosene, a waxy component including carnauba wax, and an emulsifying agent. the bath being maintained at a temperature between 100 F. and 120 F.

r ROBERT D. NEDVIDEK.

JOHN R. MacRII-L. 

